As far as satellites are concerned, of course Iridium is pretty much out of business already, and they are planning to start de-orbiting the satellites any day now. But there is at least one other commercial satellite constellation still going, which is oriented more toward data transmission (It's used to track 18-wheelers, perhaps you've seen one with a little radome on top of the cab?) You might be able to talk those people into giving you a unit in exchange for painting their name on your boat and letting them take some publicity pictures (like a race car, ya know?) > -----Original Message----- > From: Sean H. Breheny [mailto:shb7@CORNELL.EDU] > Sent: Thursday, October 19, 2000 3:02 PM > To: PICLIST@MITVMA.MIT.EDU > Subject: Re: [OT]: Long range position feedback anyone ? > > > It is indeed a really nice project idea! I hope Tobie can > make it work! > > AFAIK, There are several store and forward packet radio satellites in > orbit. These will accept packet messages (transmitted on VHF > or UHF freqs) > from ground stations and then allow other users in different locations > (anywhere in the orbital coverage of the satellite) to > receive the data at > a later time. > > How large is the boat? The amount of signal power needed for > the satellite > depends on the satellite,and since I have never done this, I > am not sure of > the typical amounts needed. I would guess ,thought, that > there is at least > one such satellite which would get a good enough signal from > a couple of > watts into a small yagi. There has been a push for a long > time in amateur > radio to launch some satellites which had such good antennas > and receivers > to be able to get a usable signal from 5 watts into an omnidirectional > antenna, but I don't know if any are currently in operation. > > Could you handle an antenna which was about 1.5 meters long > and 0.3 meters > wide? What are your weight limits like? Could you deal with > having a pair > of motors to point the antenna and a computer with tracking program to > point it properly? > > Sean > > > > At 02:41 PM 10/19/00 -0500, you wrote: > >I for one, think this is a super-cool project. > > > >I've been waiting for the ham radio types to come in, who > know more about > >the radio side, and especially what is legal. For that kind > of range, you > >need either a short-wave radio that will skip, or a > transmitter that can > >talk to a satellite. > > > >For the short-wave approach, the ham guys might know how you > can legally > >have a remote-operated transmitter off in international > waters operating on > >a short-wave ham band. If you put it up using a standard > modulation scheme > >and publish its frequency and transmission schedule, you can > probably get a > >lot of help in receiving the reports, with receivers > scattered about both > >sides of the ocean. > > > >It will take a few watts to push a signal across the ocean, > but the message > >need only be a few milliseconds long. 50 bytes at 1200 baud is 417 > >milliseconds. You should be able to use less than 50 bytes, > and possibly a > >higher bit rate as well. I would run the transmitter from a > bank of low-esr > >capacitors that were charged up from whatever power supply > you're using for > >motors, etc. If it transmits, say, every 4 hours, and has a > 50% probability > >of being received each time, then you will get an average of > three position > >reports per day. The probability of getting them all goes > way up if you > >have 10 receivers at different positions. > > > > > -----Original Message----- > > > From: Tobie Horswill [mailto:thorswil@EXMACHINA.QC.CA] > > > Sent: Thursday, October 19, 2000 1:15 PM > > > To: PICLIST@MITVMA.MIT.EDU > > > Subject: Re: [OT]: Long range position feedback anyone ? > > > > > > > > > Hi Roman, > > > > > > Well actualy, the boat is still in the making ... I'm > > > building it just > > > because I like the idea of a totally closed and autonomous > > > system, I don't > > > have the money to travel and the "hi-tech message in a > bottle" idea is > > > something I've been thinking of for some time. The boat > should start > > > somewhere off the Canadian east cost and head for France, > > > Spain or Portugal > > > and then come back. It'll be saving daily position logs to > > > EEPROM so I can > > > plot it's course but still, I'd like to have a real-time > > > position feedback > > > if possible ... And no, I don't do this often, this is the > > > first time. :-) > > > > > > Regards, > > > > > > Tobie Horswill > > > thorswil@hotmail.com > > > > > > > > > ----- Original Message ----- > > > From: "Roman Black" > > > To: > > > Sent: Thursday, October 19, 2000 1:53 PM > > > Subject: Re: [OT]: Long range position feedback anyone ? > > > > > > > > > > Hi Tobie, > > > > > > > > I'm fascinated, why do you have a little boat > roaming around > > > > the middle of the atlantic ocean? Do you do this often? :o) > > > > -Roman > > > > > > > > > > -- > > > http://www.piclist.com hint: PICList Posts must start > with ONE topic: > > > "[PIC]:","[SX]:","[AVR]:" =uP ONLY! "[EE]:","[OT]:" =Other > > > "[BUY]:","[AD]:" =Ads > > > > > > > > > > > > > > > >-- > >http://www.piclist.com hint: PICList Posts must start with ONE topic: > >"[PIC]:","[SX]:","[AVR]:" =uP ONLY! "[EE]:","[OT]:" =Other > >"[BUY]:","[AD]:" =Ads > > -- > http://www.piclist.com hint: PICList Posts must start with ONE topic: > "[PIC]:","[SX]:","[AVR]:" =uP ONLY! "[EE]:","[OT]:" =Other > "[BUY]:","[AD]:" =Ads > > > > -- http://www.piclist.com hint: PICList Posts must start with ONE topic: "[PIC]:","[SX]:","[AVR]:" =uP ONLY! "[EE]:","[OT]:" =Other "[BUY]:","[AD]:" =Ads